EVALUATION OF A SINGLE DILUTION ELISA SYSTEM FOR DETECTION OF SEROCONVERSION TO BOVINE VIRAL DIARRHEA VIRUS, BOVINE RESPIRATORY SYNCYTIAL VIRUS, PARAINFLUENZA-3 VIRUS, AND INFECTIOUS BOVINE-RHINOTRACHEITIS VIRUS - COMPARISON WITH TESTING BY VIRUS NEUTRALIZATION AND HEMAGGLUTINATION INHIBITION

A single-dilution quantitative enzyme-linked immunosorbent assay (ELIS A) system, based on commercial ELISA kits, for the simultaneous detect ion of seroconversion to bovine viral diarrhea virus (BVDV), bovine re spiratory syncytial virus (BRSV), parainfluenza-3 virus (PI3V), and in fectious bovine rhinotracheitis virus (IBRV) was evaluated by testing acute and convalescent serum pairs from 564 cattle in 145 outbreaks of respiratory disease. Seroconversion to BVDV, BRSV, PI3V and IBRV was detected in 8.0%, 19.0%, 13.7%, and 7.4%, respectively, of serum pairs tested. Seroconversion was detected in 60.7% of herds and 34.6% of an imals tested. Infection with 2 or more viruses was found in 46.6% of t hese herds and in 27.2% of these animals. The majority of BVDV infecti ons (62%) were associated with other virus infections, suggesting that BVDV may potentiate infection with other agents rather than being a p rimary pathogen of the respiratory tract. The results were compared wi th those obtained by virus neutralization and hemagglutination inhibit ion testing, and the sensitivity, specificity, and overall correlation were calculated. Sensitivities of 92%, 95%, 100%, and 100% were obtai ned for BVDV, BRSV, PI3V, and IBRV, respectively. The corresponding sp ecificity values were 89%, 92%, 86%, and 91%. The overall correlation for each virus was 90%, 93%, 90%, and 93%, respectively. These results demonstrate that this ELISA system may be used successfully to detect seroconversion in serum pairs, highlight the frequency of multiple vi ral infections in outbreaks of respiratory disease, and provide furthe r evidence of an immunosuppressive role for BVDV infections.